Year	Percent
1986	0.58
1987	0.4
1988	0.35
1989	0.49
1990	0.71
1991	0.8
1992	0.69
1993	0.69
1994	0.64
1995	0.68
1996	0.71
1997	0.57
1998	0.49
1999	0.62
2000	0.5
2001	0.58
2002	0.56
2003	0.48
2004	0.34
2005	0.39
2006	0.61
2007	0.75
2008	0.7
2009	0.81
2010	0.78
2011	0.67
2012	0.72
2013	0.87
2014	0.74
2015	0.74
2016	0.79
2017	0.63